New pseudo-scalars, often called axion-like particles (ALPs), abound in
model-building and are often associated with the breaking of a new symmetry.
Traditional searches and indirect bounds are limited to light axions, typically
in or below the KeV range for ALPs coupled to photons. We present collider
bounds on ALPs from mono-photon, tri-photon and mono-jet searches in a
model independent fashion, as well as the prospects for the LHC and future
machines. We find that they are complementary to existing searches, as they are
sensitive to heavier ALPs and have the capability to cover an otherwise
inaccessible region of parameter space. We also show that, assuming certain
model dependent correlations between the ALP coupling to photons and gluons as
well as considering the validity of the effective description of ALP
interactions, mono-jet searches are in fact more suitable and effective in
indirectly constraining ALP scenarios.